Though glass or plastics are being used as transparent substrates, they are liable to generate static electricity on the surface thereof, because such substrates are insulators. When these susbtrates such as glass or plastics are used for a display panel such as Braun tube (CRT), fluorescent indication pipe (FIP), plasma display (PDP), or liquid crystal display (LCD), static electricity is generated on the face-plate of the display panel and dust or the like is attracted thereto, whereby the displayed images on the panel becomes difficult to be visible. Particularly, in the case of LCD, there is sometimes observed destruction of IC or miss-operation of the display device caused by such static electricity as generated above.
In an electrophotographic duplicator for ordinary paper (PPC) equipped with an automatic draft feeder (ADF), when a copy is taken successively from a plurality of drafts through ADF, a contact glass plate on which the draft is placed and the draft in the sheet form fed through ADF are rubbed with each other, whereby static electricity is generated on the contact glass plate, and by virtue of the static electricity thus generated, the draft attaches to the contact glass plate and stays thereon, plugging sometimes the ADF with the drafts.
In order to inhibit the generation of static electricity on the above-mentioned substrates used for a display panel of the display device or contact glass plate of PPC, there has heretofore been used to apply a transparent substrate having thereon a transparent conductive film to the surface of said display panel or said contact glass plate.
Known hitherto as a technique of obtaining such transparent conductive substrates as mentioned above is, for example, a method wherein a transparent conductive film consisting of a metal or inorganic oxide is formed on the surface of a transparent conductive substrate by means of a dry process such as CVD, PVD, vacuum evaporation or sputtering, or a method wherein a conductive coating is formed on the surface of a substrate by means of a wet process which comprises applying a coating solution containing a conductive material such as tin oxide and a transparent matrix-forming component on the surface of a substrate followed by drying and curing.
In the dry process such as CVD referred to above, however, there are involved such problems that the film must be formed by a batchwise method using a vacuum evaporator, and that the surface area or shape of the substrate on which the film is formed is limited to depending upon the size of the vacuum evaporator used.
In the wet process mentioned above, on the one hand, there are involved such problems that the transparent conductive coating formed by using, as a transparent matrix-forming component, a binder resin such as acrylic resin, butyral resin, melamine resin or vinyl chloride/vinyl acetate copolymer resin is poor in transparency, scratch resistance, adhesion to the substrate or durability such as alkali resistance, acid resistance, water resistance or solvent resistance.
Recently, with the view of solving such problems as mentioned above, there have been proposed various coating solutions for forming conductive coatings and transparent conductive coatings formed by using such coating solutions for forming conductive coatings.
For example, Japanese Patent L-O-P Publn. No. 193971/1988 proposes conductive coatings consisting essentially of conductive particles and a vehicle (matrix), said conductive particles having an average particle diameter of at least 10 .ANG. and not more than 5 .mu.m.
Japanese Patent L-O-P Publn. No. 22340/1990 proposes molded products (transparent substrates) having thereon a transparent coating (transparent conductive coating) containing 5-80% by weight of particulate inorganic substance consisting of tin oxide having an average particle diameter of 1-300 .mu.m.
In the proposals mentioned above, there are used, as the matrices, organosilicon compounds represented by the following general formula (A). EQU R.sup.1.sub.a R.sup.2.sub.b Si(OR.sup.3).sub.4-a-b (A)
By way of Japanese Patent L-O-P Publn. No. 54613/1989, WO89/03114 and WO90/02157, the present applicant has proposed coating solutions for forming conductive coatings prepared by mixing conductive substances with partial hydrolyzates of alkoxysilane and acetylacetonatochelate such as bisacetylacetonatodialkoxy zirconium as a matrix in a mixed solvent of water-organic solvent, and substrate having on the surface thereof a transparent conductive coating obtained from the above mentioned coating solutions.
These substrates having coated thereon a transparent conductive coating as obtained above, however, are required to have further improved durability and also excellent surface smoothness, though said substrates are excellent in conductivity and transparency and also found to be at least satisfactory with respect to properties such as durability.
In the case of a display panel with a transparent conductive coating, it is requested that the quality, especially resolving power, of the images displayed by means of a display device equipped with the display panel will not be deteriorated by the presence of said transparent conductive coating.
The present invention has been made in view of such circumstances as mentioned above, and the main objects of the invention are to provide coating solutions capable of forming transparent conductive coatings excellent in adhesion, surface smoothness and durability such as alkali resistance and water resistance on the surface of substrates such as glass, plastics and the like, process for preparing the same, conductive substrates having formed on the surface thereof transparent conductive coating having such excellent properties as mentioned above, processes for preparing the same, and display devices equipped with said transparent conductive substrates.